- Sao Paulo, Action dimensions of simple complexes of groups,
March 16, 2018: pdf

- MCA, Montreal, Euler characteristics and Haken manifolds, July
27, 2017: pdf

- Fields Institute, Toronto, Action dimension of Artin groups,
June, 2016:
pdf

- Ventotene, Betti numbers of residual towers of reflection
groups, September, 2015: pdf

- Cortona, Complements of hyperplane arrangements as posets of
spaces, September, 2014: pdf

- University Sao Paulo, Orbifolds and reflection groups, May,
2014: Lecture
1, Lecture
2, Lecture
3, Lecture
4, Lecture
5

- University of Wisconsin, Milwaukee, Aspherical manifolds that
cannot be triangulated, December, 2013: pdf

- OSU, Invitations to Mathematics, September, 2013: Lecture: 1,
2

- Durham, England, same topic as below, August, 2013: pdf

- Guanajuato, Congress of the Americas, Aspherical manifolds
that cannot be triangulated, August, 2013: pdf

- Tsinghua University, Beijing, The geometry and topology of Coxeter groups, May 10, 2013: pdf
- Tampa AMS meeting, Cohomology of random graph products, March, 2012: pdf
- Bowling Green, colloquium, Coxeter groups and buildings, October, 2011: pdf
- Dubrovnik, Right angularity, flag complexes, asphericity, July 2011: pdf
- OSU, Introduction to Coxeter groups, April 2011: pdf
- Rutgers, Compactly supported cohomology of buildings, December, 2010: pdf
- BIRS (Banff), Graph products, November, 2010: pdf
- Goa, same topic as below, August, 2010: pdf
- Poznan, Cohomology computations for Coxeter groups and their relatives, June, 2010: pdf
- Oberwolfach, Cohomology computations for groups related to Coxeter groups, April 2010: pdf
- Paris 13, Cohomology of Coxeter groups and buildings, June, 2009: pdf
- Ferryfest, University of Chicago, Examples of buildings, March, 2009: pdf
- Conference in honor of Peter Orlik, Fields Institute, August, 2008: pdf
- Hangzhou, July 2008 (Summer School on Transformation Groups and Orbifolds) Lecture: 1, 2, 3, 4
- Peking University, June 2008 (Coxeter groups and nonpositive
curvature): pdf

- OSU, Examples of Groups Conference, May 2008 (Coxeter groups) Lecture 1, Lecture 2
- Milwaukee, STDC, March 2008 (Compactly supported cohomology of
buildings): pdf

- OSU, Lefschetz Colloquium, November 2007 (Introduction to
geometric group theory):
pdf

- MSRI Introduction to Geometric Group Theory Workshop, August
2007 (Cohomology of Coxeter groups and buildings):
pdf movie

- AMS special session, Oxford, Ohio, March 2007 (L^2 cohomology
of hyperplane complements):
pdf

- Morelia, January 2007 (L^2 cohomology of hyperplane
complements):
pdf

- Centre de Recherches Mathematiques, Montreal, July, 2006 (5 lectures on L^2 Betti numbers): Lecture 1, Lecture 2, Lecture 3, Lecture 4, Lecture 5
- Fayetteville, Arkansas, April 2006 (The cohomology of Coxeter
groups with group ring coefficients): pdf

- Greensboro, NC, March 2006 (Examples from Coxeter
Groups): pdf

- University of Western Ontario, February 2006 (Survey of
Coxeter groups): pdf

- Stanford, August 2005 (Weighted L^2 cohomology): pdf

- Bedlewo, Poland, July 2005 (Weighted L^2 cohomology): pdf

- AIM, June 2005 (Boundaries of groups): pdf

- LMS Lectures, July 2004 (10 lectures): pdf

- Munster, June, 2004: pdf

- Mobile, GGT conference, February, 2004 (Weighted L^2 cohomology): pdf
- Budapest, July, 2002 (Andreev's Theorem and Euler characteristics of 4-manifolds): pdf